Question

Identify the true statement. Choose one:
A. Underground coal mining is dangerous because of possible tunnel collapse and possible methane gas explosions.
B. Anthracite coal develops at depth along mountain belt borders, where temperatures reach 600°C.
C. Strip mining can be done economically down to a depth of about 1 km.
D. Coal began to form on the Earth soon after life evolved in the Precambrian.

Answer 1

Answer:

A. Underground coal mining is dangerous because of possible tunnel collapse and possible methane gas explosions.

Explanation:

Dangers of underground coal mining include asphyxiation, methane gas poisoning, tunnel collapse and explosions of methane gas, a highly flammable gas. Methane explosions occur since this gas is a byproduct of coal. This explosion can cause tunnel collapse.